Methicillin resistance and biofilm formation in Staphylococcus Aureus isolated from clinical samples in a tertiary care hospital in Central India

Abstract

Background: Staphylococcus aureus is a virulent organism resistant to most of the conventionally available antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA) is the most common cause of nosocomial infections. One of the reasons is because of its capability to produce biofilms. The increasing drug resistance along with methicillin resistance and biofilm production among the strains of Staphylococcus aureus presents a serious problem to the treatment of the infections caused by S. aureus. Objectives- To detect methicillin resistance by antibiotic susceptibility test in Staphylococcus aureus and to detect biofilm formation in the isolates and assess its correlation with methicillin resistance Material and methods- In this prospective study conducted in Tertiary care Institute, Gwalior a total of 300 isolates of S. aureus were screened for Methicillin resistance using Cefoxitin disc by Kirby Bauer Disc Diffusion method on Mueller Hinton agar. For detection of Biofilm formation, two phenotypic tests were done - Tube method (TM) and Tissue culture plate method (TCP). Results - Out of 300 isolates, 78% were MRSA and 22% were MSSA. A total of 47% isolates were Biofilm producers and 53% were non biofilm producers. Among the biofilm producers, 89.5% were MRSA and only 10.5% were MSSA, thus depicting the higher prevalence of biofilm formation among MRSA.
Conclusion- This study demonstrates the high prevalence of MRSA isolates producing biofilms in clinical staphylococcal samples. Since both are interdependent, detection of biofilm expression in clinical isolates would be beneficial in treatment decisions if done routinely.